The Protected Trust Add-in for Microsoft Outlook (here-in referred to as “the add-in”) enables users to send and receive secure messages using the familiar Microsoft Outlook e-mail interface.  This document describes how to install and configure the add-in on workstations and terminal servers.


The add-in requires the following software:

  • Microsoft Windows 7 / Server 2008 or later
  • Microsoft Outlook 2007, 2010, 2013, or 2016
  • Microsoft .NET Framework 4.0 Client Profile

The add-in is supported for use with any of the following types of e-mail servers:

  • Microsoft Exchange
    • Cached Exchange Mode
    • Online Mode
    • POP3


The add-in can be installed for all users on a computer (the default) or on a per-user basis.  Additionally, it can be installed by using the setup program (.exe) or one of the Microsoft Installer packages (.msi).

Using the Setup Program (.exe)

The current released version of the setup program can be downloaded from our website at https://protectedtrust.com/Download.

To install the add-in, execute the setup program and select either “All Users” or “Just me.” Then click “install-outlook-pt-add-inInstall Now.”  If needed, the setup program will prompt to run as an administrator account.  It will also install any required prerequisites that are not currently installed, including the Microsoft .NET Framework 4.0 Client Profile.

Command-Line Options

The setup program can also be invoked using the command-line.  Below are the available command-line options.

/allusers The add-in will be installed for all users on the computer or terminal server.  The setup program must be run as an administrator.
/currentuser The add-in will be installed only for the user running the setup program.
/immediate Installation will start immediately, without requiring user interaction.
/silent Installation will start immediately, without requiring user interaction or displaying the user interface.
/extract The setup program will extract the Microsoft Installer packages (.msi) to the current working directory and exit.  If specified, all other command-line options are ignored.

Using the Microsoft Installer Packages (.msi)

To better support enterprise deployment tools, the add-in can be installed by one of the Microsoft Installer packages.  The Microsoft Installer packages do not require any user interaction.

To acquire the installer packages, execute the setup program (.exe) with the “/extract” command-line option.  For example:


This will create two .msi files in the current working directory (where X is the current version number of the installer):

ProtectedTrustOutlookAddinX.AllUsers.msi Use this package to install the add-in for all users on a computer or terminal server.
ProtectedTrustOutlookAddinX.PerUser.msi Use this package to install the add-in on a per-user basis.


If the .NET Framework 4.0 Client Profile is not already installed on the target computer, the Microsoft Installer package installation will fail to install.

Automatic Updates

To ensure that all users have the latest features, bug, and security fixes, the add-in will automatically check for and install new available versions every 7 days.
To disable automatic updates, an administrator must install the All Users .msi with the parameter AUTOUPDATE set to FALSE.automatic-updates

Setting and Enforcing Options

Users can modify the add-in options by using the Protected Trust Options and Advanced Options dialogs.setting-and-inforcing-options

Administrators can control or enforce the value for many of these options by setting certain registry key(s).  This can be accomplished on a large scale by using Group Policy Objects (GPO) or other enterprise deployment tools.

Setting a User’s Option

To set a user’s option without using the options dialog, create or update one of the registry values listed below in the HKEY_CURRENT_USER\Software\ProtectedTrust\OutlookAddin key.setting-a-users-options

Enforcing an Option for All Users

To enforce a specific option for all users on a computer, create or update one of the registry values listed below, in the HKEY_LOCAL_MACHINE\Software\ProtectedTrust\OutlookAddin registry key.


Registry Values

Value Name Value Type Description
ProtectNewMail String (REG_SZ) Can be one of the following values:True – When a user creates a new message, the “Message Protected” button will be On.False – When a user creates a new message, the “Message Protected” button will be Off.
MessageProtectedRequired String (REG_SZ) Can be one of the following values:True – All messages will be sent using Protected Trust.False – A user can toggle the “Message Protected” button On or Off.

Sending a Diagnostics Log

The add-in maintains a Diagnostics Log that can be useful while troubleshooting issues.  This log includes basic user information, such as the type of e-mail servers that are configured, other add-ins that are installed, and a copy of the current error log.  Please remove any information you wish to not disclose from these logs before sending it.  Any information collected in the Diagnostics Log will be used only to troubleshoot issues and will be not used for any other purpose